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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: i-node who wrote (1010040)	4/6/2017 2:20:04 AM
From: Wharf Rat	Read Replies (2) \| Respond to of 1572769

"Of course they do" Of course they don't, or I wouldn't have given you a link where the differences are explained. "There is no more. " Sometimes there's less, as you would have seen in the link. Four major datasets Scientists use four major datasets to study global temperature. The UK Met Office Hadley Centre and the University of East Anglia’s Climatic Research Unit jointly produce HadCRUT4 . In the US, the GISTEMP series comes via the NASA Goddard Institute for Space Sciences ( GISS), while the National Oceanic and Atmospheric Administration ( NOAA) creates the MLOST record. The Japan Meteorological Agency ( JMA) produces a fourth dataset. Here’s how global temperatures in the four datasets compare over the past 130 years. You can see they all show a warming trend, but there are some year-to-year differences too. Global average temperature anomaly from 1880 to 2012, compared to the 1951-1980 long term average. Source: NASA Earth Observatory. Of the four datasets, GISTEMP (red line) shows the fastest warming. JMA tends to track slightly lower than the others (purple). So why do we see differences between the datasets? The answer to this lies in how the different datasets deal with having little or no data in remote parts of the world, measurement errors, changes in instrumentation over time and other factors that make capturing global temperature a less-than-straightforward task. Data coverage has, perhaps, the biggest influence. NASA GISTEMP has the most comprehensive coverage, with measurements over 99 per cent of the globe. By contrast, JMA covers just 85 per cent of the globe, with particularly poor data in the poles, Africa and Asia. HadCRUT4 and challenges in the Arctic How do the datasets deal with missing data? Nasa’s GISTEMP uses statistical methods to fill in gaps using surrounding measurements. How much each measurement influences the final value depends on how close it is geographically to the missing point. NOAA follows a similar process for the MLOST dataset. HadCRUT4 is the only dataset to leave regions with missing data blank, rather than try to fill them in. This effectively assumes temperatures there are in line with the global average. This wouldn’t be a issue if the world was warming at the same rate everywhere. But data suggests the Arctic, for example, is warming more than twice as fast as the global average. It’s reasonable then that a missing Arctic could lead to a global temperature that’s lower than in the real world. Indeed, updates to an old version of the temperature record (HadCRUT3) to include better Arctic data saw northern hemisphere temperatures rise by 0.1 degrees Celsius. But data gaps still exist, as the white areas in the top map in the figure below show. A paper last year attempted to fix this well-known issueusing satellite data to reconstruct the holes in the surface temperature record (bottom map below). Doing so suggested Earth’s surface has warmed twice as much over the past 15 years than HadCRUT4 suggests. Top: White areas show gaps in the HadCrut4 dataset. Bottom: Reconstructed data shows faster warming in the Arctic than the rest of the world. Source: Cowtan & Way (2013). A question of detail After working out the annual temperature anomalies for each land or ocean station, the next job for scientists is to divide the earth up into grid boxes. They work out the average temperature for each box by combining data from all the available stations. The smaller the grid boxes, the better the average temperature of the box will reflect the actual temperature at any given point, leading to a more accurate estimate global temperature when you add them all together. This is another point on which the datasets differ. The NASA GISTEMP record is the most detailed of the four datasets, with grid boxes two degrees longitude by two degrees latitude. The other three have grid boxes measuring five by five degrees. They also differ in how many land stations they have around the world, too. HadCRUT4 has about 5,500, GISTEMP takes middle place with about 6,300, but MLOST has the most of all, with about 7,000 land stations. The four datasets differ in other important ways, too, including the time period they cover. HadCrut4 stretches back the furthest to 1850. GISTEMP and MLOST both begin in 1880, whereas JMA starts a bit later in 1891. carbonbrief.org "you cannot just ASSUME it is because of GW. In CA and NV, it probably has a lot more to do with the fact that there have been massive population increases and little in the way of new reservoir capacity." Drought is caused by lack of rainfall, It would have been the driest stretch in 1000 years, even if we had only 500,000 people. Humans would have been (well beyond) fine with our current reservoir system, but the trees and wildlife wouldn't. The Climate Change ‘Bully’ in California’s Drought climatecentral.org "When you are dealt four blackjacks in a row, it doesn't mean you're cheating." When the professional dealer tells you that you just won 4 in a row, and the amateur denier sitting next to you says you lost all 4, and not only that, you cheated, who are you gonna listen to?